Substance that boils at room temperature: Controlling the boiling temperature

[Pisica]

TL;DR Summary

Temperature controlled boiling

1. I am looking for a non-dangerous substance that boils at room temperature.

2. And I would like this boiling temperature to be slightly variable. How can we change the boiling temperature?
Through impurities placed in the liquid? For example salt water has a higher boiling point.


I want to test an organic steam engine, that is, instead of water, test other substances that offer some advantages.

 

[.Scott]

I think the closest you're going to get is diethyl ether (about 93 F - and hazardous).
Anything that evaporates very quickly will likely be readily taken up through inhalation - and, except for water, will be hazardous.

Would dry ice (CO2) be useful to your demonstration?

 

[Borek]

How can we change the boiling temperature?

Of a single substance at a constant pressure? We can't. Lowering the pressure can help, but makes the setup complicated.

Of a mixture? Varying composition. But this is not something for light hearted, there are thick books on the subject. In most scenarios when the liquid boils off composition of the left liquid changes, so the BP changes. With some luck you can find an azeotrope that has a BP close to what you need.

When it comes to salty water google boiling point elevation and colligative properties.

 

[Pisica]

and, except for water, will be hazardous.

I clearly exclude the ether!

 

[Mayhem]

I imagine any liquid which boils at r.t. will be impossible to handle as it will still rapidly evaporate at temperatures lower than its bp.

 

[russ_watters]

Almost by definition a substance that boils at near room temperature and at reasonable pressure is a refrigerant. So that's the class of chemicals OP would be looking at. However, lacking details of what they are trying to do it's tough to specify one.

 

[Mayhem]

Almost by definition a substance that boils at near room temperature and at reasonable pressure is a refrigerant. So that's the class of chemicals OP would be looking at. However, lacking details of what they are trying to do it's tough to specify one.

Indeed. Isopentane seems to be one of the few with a r.t. boiling point (28 C) which probably isnt super toxic compared to the halogenated refrigerants in the same league.

 

[Tom.G]

According to data sheet for ISOPENTANE:
Chemical name: 2-methylbutane
IPT.pdf

Much data there
This was the only part in Red, In case of spill:

Evacuate.
Keep people away.
Wear goggles and self-contained breathing apparatus.
Shut off ignition sources and call fire department.
Avoid contact with liquid and vapor.
Stay upwind and use water spray to ``knock down'' vapor.
Notify local health and pollution control agencies.

 

[RicoGerogi]

Isopentane boils around 82°F so it's a good pick for low temp setups. You can change the boiling point a bit with salt or by messing with pressure. Keep safety in mind...it’s flammable!!

 

[Borek]

According to data sheet for ISOPENTANE:
Chemical name: 2-methylbutane
IPT.pdf

Much data there
This was the only part in Red, In case of spill:

(Iso)pentane (while light in terms of a short carbon chain, thus very volatile and low boiling, actually first of a homologous series to be liquid at STP) is very similar to every other hydrocarbon present in gasoline or natural gas, and as such not much worse nor dangerous than these.

Doesn't make it safe, but helps add perspective, this is kind of a compound we all deal with on a daily basis.

 

[Rive]

I want to test an organic steam engine, that is, instead of water, test other substances that offer some advantages.

As I see, the issue here is that any substance which is 'boiling at room temperature' will has steam pressure around room pressure => a steam engine will has some difficulties to run.

Water works because there is a pressure difference between high temperature pressurized steam and ambient, and not because it's in steam phase. You can run a steam engine on compressed air alone, but can't run it on any kind of steam on ambient pressure.

In short - you need to sort out your physics first, I think.

 

[ketoenol]

Indeed. Isopentane seems to be one of the few with a r.t. boiling point (28 C) which probably isnt super toxic compared to the halogenated refrigerants in the same league.

I think you want to be a little careful; it's not great to be breathing lots of isopentane either (OSHA PEL of 1000 ppm is similar to lots of refrigerants, in fact the NIOSH REL of 120 ppm is lower than lots of halogenated refrigerants). Those are for 8 or 10 hour workdays every day, so getting a few whiffs of it isn't going to kill you, but the same is true of R11 (trichlorofluoromethane, b.p. 23 C) and similar.

There's a reason CFCs and other halogenated compounds are super commonly used as refrigerants; they're both non-flammable and relatively non-toxic.

 

[chemisttree]

Trichlorofluoromethane has a bp of 23C or 73F. Like Russ says, it is a refrigerant. Not too hazardous unless you are an ozone molecule in the stratosphere.